[No]Parallel
The SET PARALLEL statement controls whether the query optimizer enables the generation of parallel query execution plans.
The optional degree of parallelism value indicates the number of exchange nodes (or points of concurrency) built into the plan. The default value is 4 and the maximum is 32.
The SET NOPARALLEL statement (or setting the degree of parallelism value to 0 or 1) tells the optimizer not to consider parallel query plans.
Note: When tracing the I/O or the locks of a parallel query (using SET IO_TRACE or SET LOCK_TRACE with SET PARALLEL), the trace messages from child threads of the QEP are logged to the II_DBMS_LOG. The trace messages for the main thread are sent to the user session in the normal manner.
For a discussion of parallel query plans, see the Database Administrator Guide.